Ionization devices are known for improving the air quality of indoor environments caused by two types of pollution. One type of pollution is ion depletion which occurs in tightly sealed spaces in the absence of fresh air flow. The second type of pollution is solid pollution such as cigarette smoke, dust, soot, industrial pollutants, pollen and smog. Negative ions provided by ionization devices generally reduce the discomfort of a highly pollinated atmosphere or an atmosphere having a deficiency of negative ions or a surplus of positive ions. Breathing in positive ions tends to lower the oxygen level of the blood and increases the accumulation of serotonin, a neurohormone capable of inducing adverse biological effects. Ionized air has been shown to reduce serotonin levels as well as to substantially reduce the amount of bacteria in the air.
Conventional ionization devices include an ionization electrode coupled to a source of high voltage. The ionization electrode is generally a conductive needle or a thin wire. Airborne particles which are to be precipitated from the air by electrostatic attraction to the ground are charged with extra electrons by the ionization electrode. This charging ionizes the airborne particles and removes some of the pollutants from the air.
Israel Patent 48817 describes a negative air ionization device employing a tubular shield to protect a conductive needle from accidental direct contact. In addition, this ionization device includes a grounding wire touching the ionization electrode. The grounding wire reduces an electrostatic field that forms in the vicinity of the shield so that a controlled flow of ions is produced.